In electronic signal processing, it is usually required to process a signal having low or high signal amplitude. The processing of a signal having low signal amplitude is limited by a noise spectrum. There are diverse sources generating noise, external sources as well as sources caused by effects intrinsic to an apparatus performing the signal processing. One particular noise term in semiconductor devices is so-called “flicker noise”, that is also known as “1/f-noise”. A close related low-frequency noise source to flicker noise is noise called random telegraph signals. In the following disclosure, the term “flicker noise” is used for low-frequency noise like 1/f-noise or noise due to random telegraph signals.
As indicated by its later denotation, 1/f-noise is most problematic in a low frequency spectral region. Additionally, flicker noise deteriorates the performance of non-linear circuits, e.g. having low frequency flicker noise being mixed and/or translated to higher frequencies in devices, such as frequency mixers, and controlled oscillators.
In battery-driven circuits, where signal-to-noise ratio may be improved at the cost of a higher power consumption, a reduction of flicker noise is desired. In large volume applications, where signal-to-noise ratio may be improved at the cost of a higher larger circuit area, a reduction of flicker noise is desired as well.
According to conventional design methods in semiconductor circuits, flicker noise is widely considered a limiting effect to signal processing.